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Core Java - Interview Questions and Answers for 'Optional' - 3 question(s) found - Order By Newest

Not frequently asked as it was introduced with Java 8.
 Q1. What is the use of Optional ?Core Java
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Ans. Optional is a good way to protect application from runtime nullPointerException in case the the absent value has been represented as null. So basically Optional class provides the type checking during compile time and hence will never result in NPE.

For ex -

List> intList = new ArrayList>();
intList.add(Optional.empty());
intList.add(Optional.of(new Employee("abc")));
intList.add(Optional.of(new Employee("xyz")));
intList.add(Optional.of(new Employee("123")));
System.out.println(intList.get(0).getName());

So Now , even when the first list element is empty, this code will never throw an NullPointerException.

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   Like         Discuss         Correct / Improve     java   java8   java 8   optional


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 Q2. Is it ok to use optional everywhere just to get over nullpointerexception ?Core Java2017-05-23 08:16:28

Ans. Optional is to be used for arguments / atrributes which are indeed optional i.e the request should continue even if they aren't provided. It should not be used for mandatory attributes or arguments as we would like application to shout out ( with error message / exception trace ) to signify a problem.

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   Like         Discuss         Correct / Improve     optional  nullpointerexception  java8  java 8     Asked in 1 Companies


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  What is the use of Optional ?
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Rarely asked as it was introduced with Java 8.
 Q3. Name few "Optional" classes introduced with Java 8 ?Core Java
Admin
info@buggybread.com
Ans. http://www.buggybread.com/2015/01/java-optional-classes-and-interfaces.html

 Help us improve. Please let us know the company, where you were asked this question :   

   Like         Discuss         Correct / Improve     java   optional   java 8   java8


Related Questions

  Difference between final and effectively final ? Why is effectively final even required ?
  What is StringJoiner ?
 Why can't we have diamond problem with interfaces ?
  What is the use of Optional ?
 Is it ok to use optional everywhere just to get over nullpointerexception ?
  What are new features introduced with Java 8 ?
  What is the @FunctionalInterface annotation ?
  Difference between DoubleSummaryStatistics , IntSummaryStatistics and LongSummaryStatistics ?
  What are the changes in Java.io in Java 8 ?


 Q4. Optional has been introduced in Java 8 to get away with which of following exception ?Core Java
a. ArithmeticException
b. ParseException
c. NullPointerException
d. FileNotFoundException

Ans.c. NullPointerException


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